Airbag systems for protecting the passengers of a vehicle are installed in a steering wheel in the driver's seat, a passenger-side dashboard, and other places, and airbags are covered with and placed behind airbag covers. In the event of an impact such as a collision, the airbag systems deploy so that the airbag covers tear open and the airbags inflate to soften the impact on the passengers.
The airbag stored in the steering wheel in the driver's seat is large enough to cover the passenger when the airbag inflates. Thus, even when the airbag is stored in a folded state, it requires a certain storage space. That is, the airbag cover, which the airbag comes out of, also requires a relatively large area. Accordingly, in general, there is nothing except for an emblem or the like in the center portion of the steering wheel storing the airbag cover.
Meanwhile, steering switches such as buttons or input sensors with which input operation can be performed for on-board equipment may be placed on the steering wheel. For instance, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2007-504983 (Patent Literature 1) describes small touch sensors provided on the spokes of a steering wheel and an airbag cover.